Noise and macro

I do a lot of macro photography, and recently have been pushing it with the addition of extension tubes. I notice that, if I increase the ISO beyond 400, the noise level becomes really noticeable. Is this an inevitable effect of the magnification?

To answer you question. If you take a light reading of the subject, the background will be under exposed. Noise will show up. This is true for most anything. A bird in a tree, the background is usually underexposed. Even if you use long exposure, some of the background will be under exposed. Noise will show. Adding the extensions, will lower the light hitting the sensor. So, you need to have more light.... someway.